Class Gastropoda Cuvier, 1795
Family Rissoidae Gray, 1847
Genus Alvania Risso, 1826
Species Alvania lactea (Michaud, 1836)
Alvania lactea (Michaud, 1836)
Common in yellow sands, in the surroundigs of San Gimignano (Siena). Pliocene (Piacenzian).
Gastropoda Rissoidae Alvania Alvania lactea Pliocene
Original Description – Descrizione originale
(O.D.) Testâ parvâ, ventricosâ subperforatâ; brevi semper lacteâ; longitudinaliter costulatâ; transversim striatâ; anfractifbus quinis convexis, supernè submarginatis; suturâ profundâ; aperturâ ovali; labro intus nilido, acuto; columellâ subcallosâ; apice subacuto.
Longueur, 3 lignes; diamètre 2 lignes.
Coquille d’un blanc un peu bleuâtre, dont les petites côtes longitudinales et les stries transversales forment un réseau granuleux très fin ; les tours de spire sont accompagnés, dans leur partie supérieure d’un très petit angle saillant qui semblerait recouvrir la suture ; de là vient an petit sinus dans la partie supérieure de l’ouverture, qui est ovoide; bord latéral tranchant; columelle calleuse.
SEM – Protoconca due giri con nucleo ornato d’irregolari linee papillose, alternate da due serie di papille disposte in modo disordinato. L’ornamentazione del secondo giro è assai diversa da quella del nucleo. Sulle prime due file presso la sutura anteriore le papille sono piccole, numerose e assai appressate. Sulle due file successive le papille sono già più rade e meno elevate. Nella parte posteriore del giro pur mantenendo un andamento spirale sono più distanziate e poco elevate (Chirli, 2006)
Two whorls of protoconch with nucleus ornamentated with irregular papillose lines, alternated by two series of papillae arranged in a disorderly mode. The ornamentation of the second whorl is very different from that of the nucleus, there are, near the anterior suture, two threads where the papillae are small, numerous and very close, in the next two threads, the papillae are already more sparse and less elevated. At the back of the whorl, while maintaining a spiral pattern, they are more spaced and not very high.
Bibliographic references and some more common synonyms
1836 Rissoa lactea – Michaud, p. 7, figs 11-12
1889 Massottia dojerleini – Monterosato, p. 33
1895 Alvania (Massotia) lactea v. semiacostata – Sacco, p. 28, fig. 69
1895 Alvania (Massotia) lactea v. fusulatovaricosa – Sacco, p. 28, fig. 70
2006 Alvania lactea – Chirli, p. 23, pl. 10, figs 9-16
2008 Alvania lactea – Chirli & Linse, p. 79, pl. 22, figs 1a-e
2021 Alvania lactea – Chirli & Forli, p. 137, pls 106, 107, 108, figs C1-9, A1-19, A1-4
Stratigraphic distribution
Pliocene – Italy and Spain. Pleistocene – Italy, Balearic Islands and Rhodes. Recent – Atlanto-mediterranean species, Tangier, Casablanca, lives on the algae of the mud-debris bottoms in the sublittoral zone.
References
Chirli C. (2006). Malacofauna Pliocenica Toscana – Caenogastropoda. Vol. 5, pp. 144, 46 Plates.
Chirli C. & Linse U. (2011). The Pleistocene Marine Gastropods of Rhodes Island (Greece). Tavarnelle, The authors. 447 pp.; 90 plates.
Michaud A. L. G. (1830). Description de plusieurs espèces de coquilles du genre Rissoa. Lyon: Perrin. 19 pp., 1 pl. , available online at http://www.linneenne-lyon.org/depot/3906.pdf
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Acknowledgements
Si ringrazia l’amico Carlo Chirli (Tavarnelle, Firenze) per la concessione all’uso di alcuni suoi testi. See also Edizioni Danaus
